Manufacture of shaped objects from cellulose derivatives



Patented Nov. 13, 1934 UNITED STATES PATENT OFFICE MANUFACTURE OF SHAPED OBJECTS FROM CELLULOSE DERIVATIVES No Drawing. Application August 28, 1929, Serial No. 389,081. In Germany July 10, 1928 4 Claims.

Ouipresent invention relates to a process of manufacturing shaped articles from cellulose derivatives of higher fatty acids and more particularly to. a process of pre-treating the material used for this purpose.

The gist of our invention will be seen from the following specification.

When cellulose derivatives of the higher fatty acids are pressed in fibrous or pulverulent form to produce plates, the latter are found to have only little elasticity. If such a plate is curved or bent, it nearly always breaks, although in the case of many cellulose derivatives of low melting point this phenomenon may be delayed for 8-10 days. Objects formed by other methods also have low elasticity; for instance, when loose cellulose derivatives of the kind in question are formed in an extrusion press into cylindrical rods, the product is easily broken.

According to this invention, shaped objects of comparatively high elasticity are produced by subjecting the fibrous or pulverulent cellulose derivative of a higher fatty acid to a rolling or calendering pretreatment, preferably at a raised temperature, and then forming it into the desired object. This pre-treatment may be carried out with the calendering machines used in the oaoutchouc industry with a pressure of about 1-100 atmospheres or more and at a temperature 3 up to 200 C., but we prefer a temperature of about 40100 C. This pre-treatment produces a profound homogenizing of the cellulose derivative, whereby at the same time an orientation of the cellulose derivative of the higher fatty acid 3 characterized by its long chains, may occur.

This orientated structure manifests itself in that sheets thinly rolled out show a pronounced direction of breaking. When breaking the sheets in another direction the fracture always tries to pass over in the pronounced breaking direction due to .the orientated structure of the sheet. When, for example, a cellulose butyroricinoleate is fashioned into a plate of 2 mm. thickness by compression in fibrous form, the product is brittle and capable of fracture in any direction when bent in an angle of 180". However, when the same parent material is first worked by rollers according to this invention, the rolled material shows a certain brittleness in the direction of rolling but not in the direction transverse to this.

When treating the calendered sheet on its surface with a swelling agent, for instance with a chlorinated hydrocarbon and an alcohol with a boiling point higher than that of the hydrocarbon, a striped structure of the sheet is clearly recognized.

Plates, rods, tubes or the like made by compression from a cellulose derivative pre-treated in this manner show surprising elasticity, and even when they are very thick they will suffer curvature and even bending without loss of pliancy.

The invention is applicable to cellulose derivatives of all the saturated and unsaturated, substituted or non-substituted higher fatty acids containing more than 8 carbon atoms,.for instance cellulose laurate, ethyl cellulose palmitate, cellulose acetostearate, cellulose butyro-ricinoleate, cellulose naphthenate.

Besides the radicals of the higher fatty acids, the cellulose molecule may also contain other substitutents.

If desired, there may be incorporated with the cellulose derivative during the rolling treatment, a filling material, a pigment or a dyestuff.

As an example of the invention a fibrous cellulose trilaurate may be rolled between two rollers for 30 minutes at 60-70 C. During the operation the material is several times twisted and turned so that it may be completely homogenized. From the material thus treated plates, rods, tubes and coatings of high elasticity may be made.

The term higher fatty acid as used in the specification and the claims is intended to include fatty acids of more than 8 carbon atoms.

What we claim is:-

1. In the manufacture of shaped articles of cellulose trilaurate the step which comprises subjecting fibrous cellulose trilaurate for 30 minutes to a rolling treatment in the same direction at a temperature of 60 to 70 C. before giving the cellulose derivative the desired shape. 2. In the manufacture of shaped articles of a cellulose derivative of a higher fatty acid the step which comprises subjecting the said cellulose derivatives to a repeated rolling treatment in the same direction with simultaneous application of heat under a pressure of at least 1 atmosphere before the shaping operation.

3. In the manufacture of shaped articles of a cellulose derivative of a higher fatty acid the step which comprises subjecting the said cellulose derivative to a repeated rolling treatment in the same direction under a pressure of 1 to 100 atmospheres at a temperature of 40 to 100 C.

4, Sheets containing cellulose derivatives of higher fatty acids, said sheets having an orien- 

